Shallow groundwater of the huge deltaic systems of Asia like the Red River Delta in Vietnam is often enriched in inorganic arsenic (As), threatening the health of millions of residents. The massive abstraction of groundwater in these areas locally causes an irreversible mixing of arsenic-free groundwater resources with arsenic-rich groundwater. Increased concentrations of competitive anions, especially phosphate (PO43-), decrease the immobilization capacity of the sediments. During transport, the mobility of dissolved As in local aquifers is strongly influenced by adsorption to sedimentary and ubiquitously occurring iron(oxyhydr)oxides. Additionally, arsenic-rich groundwater is often enriched in reduced iron (Fe2+) as well, which is capable to react with iron(oxyhydr)oxides, thereby inducing mineral transformations. Such transformations permanently affect the arsenic adsorption and immobilization capacity of the sediments.Within the scope of this research project, the underlying mechanisms related to As transport and the resulting threat to arsenic-free groundwater resources will be characterized in cooperation with the Swiss Federal Institute of Aquatic Science and Technology (Eawag). The research concept aims at assessing the complex interactions within the arsenic-iron-phosphate-system under field conditions at a study site next to the Red River. First, filtration experiments using local groundwater enriched in As and PO43- will be used to determine the As adsorption capacity of different and previously geochemically characterized iron(oxyhydr)oxides. In a second step, sample carrier containing As loaded iron(oxyhydr)oxides will be introduced into surface near aquifer parts of the study site (via existing groundwater monitoring wells). These samples will be exposed to local groundwater characterized by increased As, Fe2+ and PO43- concentrations for the following nine months. Using the in situ exposition of predefined iron(oxyhydr)oxides, it will be possible to distinguish potential mineral transformations and their influences on the As immobilization capacity of the respective iron(oxyhydr)oxides. By combining the results and outcomes of the field experiments, new and important conclusions regarding the mobility of As can be drawn. The data can be used to create a hydrochemical transport model describing reactive As transport within the investigation area. In addition, the results of the in situ exposition experiments will allow to draw conclusions in respective to the long term As immobilization capacity of different iron(oxyhydr)oxides, which is an essential information regarding in situ decontamination techniques.
Almond in California represents an agroecosystem pollinated solely by a single species, the European honey bee, a species that is becoming increasingly difficult and expensive to manage due to substantial, unpredictable mortality. Therefore, sustainable and high output production require a more integrated approach that diversifies sources of pollination. For this purpose, detailed data of our understanding how diversity can stabilize pollination are required. The project will identify alternative wild pollinator species and collect high quality data contributing to our understanding of how diversity (pollen and insects) can bolster honey bee pollination during stable and unstable climatic conditions. The research will be carried out on almond orchards in Northern California known to be either pollinator species rich (up to 30 species) or depauperate (honey bees only). The replicated extremes in pollinator diversity represent a unique opportunity to study the effects of diversity on pollination in real agroecosystems combined with laboratory and glasshouse experiments. The overall goal is to provide basic research that is essential for our general understanding of how insect diversity can affect high-quality pollination under land use and climate change.
During microbial turnover of organic chemicals in soil, non-extractable residues (NER) are formed frequently. Studies on NER formation usually performed with radioisotope labelled tracer compounds are limited to localisation and quantitative analyses but their chemical composition is left unknown. Recently, we could show for 2,4-dichlorophenoxyacetic acid and ibuprofen that during microbial turnover in soil nearly all NER were derived from microbial biomass, since degrading bacteria use the pollutant carbon for their biomass synthesis. Their cell debris is subsequently stabilised within soil organic matter (SOM) forming biogenic NER (bioNER). It is still unknown whether bioNER are also formed during biodegradation of other, structurally different compound classes of organic contaminants. Therefore, agricultural soil will be incubated with labelled compounds of five classes of commonly used and emerging pesticides: organophosphate, phenylurea, triazinone, benzothiadiazine and aryloxyphenoxypropionic acid. The fate of the label will be monitored in both living and non-living SOM pools and the formation of bioNER will be quantified for each compound over extended periods of time. In addition, soil samples from long-term lysimeter studies with 14C-labelled pesticide residues (e.g. triazine, benzothiazole and phenoxypropionic acid group) will be also analysed for bioNER formation. The results will be summarised to identify the metabolic conditions of microorganisms needed for bioNER formation and to develop an extended concept of risk assessment including bioNER formation in soils.
Soil structure determines a large part of the spatial heterogeneity in water storage and fluxes from the plot to the hillslope scale. In recent decades important progress in hydrological research has been achieved by including soil structure in hydrological models. One of the main problems herein remains the difficulty of measuring soil structure and quantifying its influence on hydrological processes. As soil structure is very often of biogenic origin (macropores), the main objective of this project is to use the influence of bioactivity and resulting soil structures to describe and support modelling of hydrological processes at different scales. Therefore, local scale bioactivity will be linked to local infiltration patterns under varying catchment conditions. At hillslope scale, the spatial distribution of bioactivity patterns will be linked to connectivity of subsurface structures to explain subsurface stormflow generation. Then we will apply species distribution modelling of key organisms in order to extrapolate the gained knowledge to the catchment scale. As on one hand, bioactivity influences the hydrological processes, but on the other hand the species distribution also depends on soil moisture contents, including the feedbacks between bioactivity and soil hydrology is pivotal for getting reliable predictions of catchment scale hydrological behavior under land use change and climate change.
The sorption of anions in geotechnical multibarrier systems of planned high level waste repositories (HLWR) and of non-ionic and organic pollutants in conventional waste disposals are in the center of recent research. In aquatic systems, persistent radionuclides such as 79Se, 99Tc, 129I exist in a form of anions. There is strongly increasing need to find materials with high sorption capacities for such pollutants. Specific requirements on barrier materials are long-term stability of adsorbent under various conditions such as T > 100 C, varying hydrostatic pressure, and the presence of competing ions. Organo-clays are capable to sorb high amounts of cations, anions and non-polar molecules simultaneously having selectivity for certain ions. This project is proposed to improve the understanding of sorption and desorption processes in organo-clays. Additionally, the modification of material properties under varying chemical and thermal conditions will be determined by performing diffusion and advection experiments. Changes by sorption and diffusion will be analyzed by determining surface charge and contact angles. Molecular simulations on models of organo-clays will be conducted in an accord with experiments with aim to understand and analyze experimental results. The computational part of the project will profit from the collaboration of German partner with the group in Vienna, which has a long standing experience in a modeling of clay minerals.
Dissolved organic matter (DOM) is one major source of subsoil organic matter (OM). P5 aims at quantifying the impact of DOM input, transport, and transformation to the OC storage in the subsoil environment. The central hypotheses of this proposal are that in matric soil the increasing 14C age of organic carbon (OC) with soil depth is due to a cascade effect, thus, leading to old OC in young subsoil, whereas within preferential flowpaths sorptive stabilization is weak, and young and bioa-vailable DOM is translocated to the subsoil at high quantities. These hypotheses will be tested by a combination of DOC flux measurements with the comparative analysis of the composition and the turnover of DOM and mineral-associated OM. The work programme utilizes a DOM monitoring at the Grinderwald subsoil observatory, supplemented by defined experiments under field and labora-tory conditions, and laboratory DOM leaching experiments on soils of regional variability. A central aspect of the experiments is the link of a 13C-leaf litter labelling experiment to the 14C age of DOM and OM. With that P5 contributes to the grand goal of the research unit and addresses the general hypotheses that subsoil OM largely consists of displaced and old OM from overlying horizons, the sorption capacity of DOM and the pool size of mineral-associated OM are controlled by interaction with minerals, and that preferential flowpaths represent 'hot spots' of high substrate availability.
Organotin and especially butyltin compounds are used for a variety of applications, e.g. as biocides, stabilizers, catalysts and intermediates in chemical syntheses. Tributyltin (TBT) compounds exhibit the greatest toxicity of all organotins and have even been characterized as one of the most toxic groups of xenobiotics ever produced and deliberately introduced into the environment. TBT is not only used as an active biocidal compound in antifouling paints, which are designed to prevent marine and freshwater biota from settlement on ship hulls, harbour and offshore installations, but also as a biocide in wood preservatives, textiles, dispersion paints and agricultural pesticides. Additionally, it occurs as a by-product of mono- (MBT) and dibutyltin (DBT) compounds, which are used as UV stabilizer in many plastics and for other applications. Triphenyltin (TPT) compounds are also used as the active biocide in antifouling paints outside Europe and furthermore as an agricultural fungicide since the early 1960s to combat a range of fungal diseases in various crops, particularly potato blight, leaf spot and powdery mildew on sugar beet, peanuts and celery, other fungi on hop, brown rust on beans, grey moulds on onions, rice blast and coffee leaf rust. Although the use of TBT and TPT was regulated in many countries world-wide from restrictions for certain applications to a total ban, these compounds are still present in the environment. In the early 1970s the impact of TBT on nontarget organisms became apparent. Among the broad variety of malformations caused by TBT in aquatic animals, molluscs have been found to be an extremely sensitive group of invertebrates and no other pathological condition produced by TBT at relative low concentrations rivals that of the imposex phenomenon in prosobranch gastropods speaking in terms of sensitivity. TBT induces imposex in marine prosobranchs at concentrations as low as 0,5 ng TBT-Sn/L. Since 1993, for the littorinid snail Littorina littorea a second virilisation phenomenon, termed intersex, is known. In female specimens affected by intersex the pallial oviduct is transformed of towards a male morphology with a final supplanting of female organs by the corresponding male formations. Imposex and intersex are morphological alterations caused by a chronic exposure to ultra-trace concentrations of TBT. A biological effect monitoring offers the possibility to determine the degree of contamination with organotin compounds in the aquatic environment and especially in coastal waters without using any expensive analytical methods. Furthermore, the biological effect monitoring allows an assessment of the existing TBT pollution on the basis of biological effects. Such results are normally more relevant for the ecosystem than pure analytical data. usw.
It has been suggested that dying and decaying fine roots and root exudation represent important, if not the most important, sources of soil organic carbon (SOC) in forest soils. This may be especially true for deep-reaching roots in the subsoil, but precise data to prove this assumption are lacking. This subproject (1) examines the distribution and abundance of fine roots (greater than 2 mm diameter) and coarse roots (greater than 2 mm) in the subsoil to 240 cm depth of the three subsoil observatories in a mature European beech (Fagus sylvatica) stand, (2) quantifies the turnover of beech fine roots by direct observation (mini-rhizotron approach), (3) measures the decomposition of dead fine root mass in different soil depths, and (4) quantifies root exudation and the N-uptake potential with novel techniques under in situ conditions with the aim (i) to quantify the C flux to the SOC pool upon root death in the subsoil, (ii) to obtain a quantitative estimate of root exudation in the subsoil, and (iii) to assess the uptake activity of fine roots in the subsoil as compared to roots in the topsoil. Key methods applied are (a) the microscopic distinction between live and dead fine root mass, (b) the estimation of fine and coarse root age by the 14C bomb approach and annual ring counting in roots, (c) the direct observation of the formation and disappearance of fine roots in rhizotron tubes by sequential root imaging (CI-600 system, CID) and the calculation of root turnover, (d) the measurement of root litter decomposition using litter bags under field and controlled laboratory conditions, (e) the estimation of root N-uptake capacity by exposing intact fine roots to 15NH4+ and 15NO3- solutions, and (f) the measurement of root exudation by exposing intact fine root branches to trap solutions in cuvettes in the field and analysing for carbohydrates and amino acids by HPLC and Py-FIMS (cooperation with Prof. A. Fischer, University of Trier). The obtained data will be analysed for differences in root abundance and activity between subsoil (100-200 cm) and topsoil (0-20 cm) and will be related to soil chemical and soil biological data collected by the partner projects that may control root turnover and exudation in the subsoil. In a supplementary study, fine root biomass distribution and root turnover will also be studied at the four additional beech sites for examining root-borne C fluxes in the subsoil of beech forests under contrasting soil conditions of different geological substrates (Triassic limestone and sandstone, Quaternary sand and loess deposits).
When released into surface waters, engineered inorganic nanoparticles (EINP) can be subject to multiple transformations. The objectives of MASK are to understand under which conditions EINP in aquatic systems will attach to suspended matter, under which conditions and in which time scale EINP are coated by NOM present in freshwater systems, how these coated colloidal particles are stabilized in the aquatic system and to which extent the aquatic aging processes are reversible. Homo-aggregation, coating changes, biological interactions and hetero-aggregation are hypothesized as key processes governing EINP aging in water bodies. In process orientated laboratory incubation experiments (50 ml to 6 l) with increasing complexity, MASK unravels the relevance and the interplay of inorganic colloids, aquagenic and pedogenic organic matter and solution physicochemistry for stability of EINP. These systems will successively approach situations in real waters. MASK thus provides information on EINP fluxes in the aquatic compartment, their time scales, reversibility and relative relevance. EINP will be analysed by standard light scattering techniques, ICP-MS, ESEM/EDX, WetSTEM and AFM. A method coupling hydrodynamic radius chromatography (HDC) with ICPMS recently developed by K. Tiede for nAg0 will be optimized and developed for further EINP analysis, MASK is further responsible for the virtual subproject ANALYSIS, the development and optimization of joint research unit methods of EINP analysis, sample preparation and sample storage, the exchange of methods and coordinates the joint analyses and the central EINP database.
Zielsetzung und Anlass des Vorhabens: Ziel der letzten Projektphase war es, mit einer Langzeit-Praxiserprobung das zweistufige biologische Verfahren zur Deponiesickerwasserreinigung als Stand der Technik zu etablieren und zu bilanzieren. Nach der Inbetriebnahme des Technikums am Deponiestandort Schöneiche ging es in der zwölfmonatigen Laufzeit des Projektes AZ 14996/04 in den Langzeitversuchen um die Validierung der Laborergebnisse im technischen Maßstab, die verfahrenstechnische Optimierung der Anlage und um eine damit verbundene mögliche Kostenreduzierung des Systems. Darstellung der Arbeitsschritte und der angewandten Methoden: Nach dem ersten Technikums-Probebetrieb wurde eine Reihe von Optimierungsmaßnahmen durchgeführt: - der Umbau des Rohsickerwasserzulaufs, - die Verwendung von Soda statt Bicarbonat für die Ammoniumoxidation in Reaktor 2, - der Einsatz von Membrandosierpumpen mit integrierten Rückschlagventilen für die Zugabe von Soda und Essigsäure, - der Einbau von zusätzlichen Polyurethan-Festbetten zur Vergrößerung der Oberfläche für die Besiedlung mit Mikroorganismen, - die Einstellung des Sollwerts für Reaktor 4 auf einen pH-Wert von 6,5, - ein Update der SPS-Steuerung der Nanofiltration zur freien Programmierung der Spülzyklen, - der Einbau eines Absperrhahns vor den Nanofiltrations-Vorfilter - und die Trennung des Nanofiltrationsablaufs vom Reaktoren-Sammelablauf zur Behälterleerung. Es wurde sowohl Rohsickerwasser der MEAB-Deponie Schöneiche als auch Sickerwasserkonzentrat der Deponie Vorketzin behandelt. Fazit: Wegen der durchgeführten Optimierungsmaßnahmen ist es prinzipiell gelungen, das Schöneicher Rohsickerwasser gemäß Anhang 51 der Abwasserverordnung aufzureinigen. In Vorketzin wurde die organische Belastung über 70% und Stickstoff über 80% reduziert. Nach Rückgang der Calciumfracht sollte es zukünftig möglich sein, mit der Zweistufen-Biologie das Sickerwasserkonzentrat ausreichend zu reinigen, da organische Belastung und Stickstoffgehalt geringer als im Schöneicher Rohsickerwasser sind. Um das Verfahren als Stand der Technik, vor allem für die Behandlung von Sickerwasserkonzentraten, zu etablieren, müssten die Laborvorgaben mit den Erfahrungen des Technikumsbetriebs kombiniert und in einer weiteren Versuchsreihe unter optimierten Bedingungen verifiziert werden.
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